CHICAGO (AP) - Years ago, the U.S. Environmental Protection Agency helped develop technology eventually used by an independent laboratory to catch Volkswagen's elaborate cheating on car emissions. But EPA used the technology primarily testing trucks, not passenger cars, because such heavy equipment was a bigger polluter.

CHICAGO (AP) Years ago, the U.S. Environmental Protection Agency helped develop technology eventually used by an independent laboratory to catch Volkswagen's elaborate cheating on car emissions. But EPA used the technology primarily testing trucks, not passenger cars, because such heavy equipment was a bigger polluter.

That decision meant that the U.S. regulator missed its best chance to foil the German carmaker's deception early. The system EPA pioneered might have subjected VW diesel cars to road tests and discovered they were spewing far above allowable levels of a key pollutant.

Without that test, VW was virtually home free and evaded detection for seven years.

The EPA says it doesn't have the money to test every vehicle, and critics say it relies too much on automakers to self-report data in an honor system.